Torque transfer drives for use with an engine in an automotive vehicle driveline may include a spiral, one-way clutch such as the clutch shown in U.S. Pat. No. 5,638,931 and 4,341,294, which issued to John H. Kerr. The Kerr clutch consists of inner and outer clutch rings with rollers that are located between the races. The rollers are engageable with spiral surfaces formed on the inner surface of the outer race and the on the outer surface of the inner race. The rollers are arranged in segments that are peripherally spaced about the axis of the clutch.
The inner race of the Kerr design is split. It surrounds a torque delivery shaft and is engageable with the outer shaft surface. A slight frictional drag at the shaft surface exists as the shaft rotates relative to the inner race. When the shaft rotates relative to the inner race, the inner race tends to follow the motion of the shaft because of the frictional drag. This causes the rollers to climb spiral surfaces and produces a radial inward force on the split inner race, which significantly increases the frictional drag. This effects a self-energizing lockup of the clutch. The locking action occurs in both directions of relative rotation of the races.
In an alternate design of Kerr, the races are formed with peripherally spaced recesses that receive clutch rollers. Bidirectional control of the torque transfer between the inner race and the shaft can be achieved with the alternate Kerr design by alternately restraining circumferential motion of the ends of the split inner race. When one end of the inner race is prevented from shifting angularly, the rollers will not effect a wedging state to lock up the clutch when relative motion of the shaft occurs in one direction. When angular motion of both ends are restrained, the clutch inner race would be centered relative to the outer race, thereby permitting overrunning motion of the shaft regardless of the direction of rotation of the shaft relative to the inner race.
Although a bidirectional clutch of the type developed by Kerr is usable in an accessory drive for an automotive vehicle driveline, it could not successfully be used in a multiple-ratio torque transmission mechanism wherein both rotation of the inner cam ring and the outer housing and coasting engine braking would be required. To achieve coasting engine braking, the clutch must instantaneously switch lockup directions upon a torque reversal. This would require an actuator with a high response rate. Further, the actuator would require a reliable sensor to trigger the operation of the clutch at the instant the torque reversal event occurs or at the instant the actuator is triggered in response to an inference of a torque reversal.